That’s part of the AC housing if I’m not mistaken. I have an fj60 not the hj and mine is blowing hot air at my feet right now. It’s shaped a bit different than yours.
You might learn how to work with fiberglass and resin. I plan on doing my dash and a few panels that are cracked here and there.I managed to glue mine back together (image provided), but I don't think it will hold in the long run. I did have a look at the part number provided, I'm just not sure if it is for the whole part and if it is the same at mine. I went into Toyota a while back and the guy couldn't find anything either. View attachment 2516746